1. Field of the Invention
The present invention relates to an information processing apparatus, information processing system, and data communication method, in which a plurality of devices are connected through a high-speed serial switch fabric that can perform a mapping of traffic classes capable of differentiating traffics onto virtual channels.
2. Description of the Related Art
In general, in information processing apparatuses that handle image data and other data, such as digital copiers and multifunction products (MFPs), a peripheral component interconnect (PCI) bus is used as an interface between devices.
However, in a parallel-type PCI bus, there are problems of racing and skews, for example, and its transfer rate is low at this stage for use in high-speed image forming apparatuses with high image quality. In recent years, in place of a parallel-type interface such as a PCI bus, a high-speed serial interface such as IEEE 1394 or USB has been considered for use. For example, according to Japanese Patent Application Laid-Open No. 2001-016382, the use of a high-speed serial interface such as IEEE 1394 or USB is suggested for use as an internal interface.
Another high-speed serial interface suggested is PCI Express (registered trademark), which is a succeeding version of the PCI bus standard and is now at the stage of actual use (for example, refer to “Outline of the PCI Express Standard,” Takashi Satomi, Interface, July 2003). Briefly, this PCI Express system is configured as a data communication network with a tree structure, such as a root complex-switch (arbitrary layer)-device as shown in FIG. 1 in “Outline of the PCI Express Standard,” Takashi Satomi, Interface, July 2003.
In recent years, the Advanced Switching Interconnect standard, which is a high-speed serial switch fabric based on the PCI Express architecture, has been laid out. This Advanced Switching Interconnect supports a wider range of applications while still adopting the technology regarding the physical layer and the link layer for PCI Express high-speed serial transmission, and its connection targets are assumed to be Chip-to-Chip and Board-to-Board. According to this Advanced Switching Interconnect, traffic classes are mapped to virtual channels, thereby making it possible to differentiate (assign priorities to) traffics.
However, even if such an interface as PCI Express is used as an interface between devices, problems to be solved still exist. Such problems are, generally, insufficient traffic control, impossible multi-host, restricted expandability, and others.